Prior art motorcycles typically include an engine mounted within a frame. One such frame includes an upper portion running generally horizontally, a front portion extending downwardly from the upper portion at the front of the motorcycle, a lower portion extending rearwardly from the bottom of the front portion, and a swing arm mounting portion at the rear of the frame. The front, lower, and swing arm mounting portions of the frame typically include spaced-apart, generally parallel tubular members.
In such prior art motorcycles, the engine is commonly mounted to the frame with fasteners at the front of the engine, the bottom of the engine, and the top of the engine. The bottom of the engine is typically mounted to a cross member joining the tubular members of the lower portion of the frame, and the cross member is usually machined to provide a level surface for the engine. The top of the engine is usually mounted to the upper portion of the frame with a bolt. A first fastener is typically used to mount one side of the front portion of the engine to one of the tubular members of the front portion, and a second fastener is used to mount the other side of the front portion of the engine to the other front portion member of the frame.
Some prior art engines are mounted to the transmission assembly along a horizontal interface with generally vertical fasteners. Alternatively, the engine and transmission are independently mounted to the frame and are then aligned with each other without directly attaching the engine to the transmission. In such motorcycles, a drive chain or belt housing interconnects the engine and transmission assembly.
One well-known classic motorcycle includes a seat post extending from the seat down between the engine and transmission to a cross member joining the tubular members of the lower portion of the frame. Many motorcycle riders and enthusiasts agree that it is desirable to maintain this classic look.